Digital tachographs for recording vehicle driving states are used mainly in the transport industry for various purposes, for example, to perform operation management for individual drivers or to give safety guidance. JP-A-2013-190886 discloses a technology for analyzing vehicle data acquired by digital tachographs and evaluating the driving contents in terms of safety, fuel efficiency, and so on, such that drivers can look back on their driving contents and drive more safely and economically.
The technology disclosed in JP-A-2013-190886 evaluates the driving contents of drivers, regardless of the types of vehicles which the drivers have operated. In the case where drivers have driven different types of vehicles, if their driving contents are evaluated in the same way, it is difficult to correctly compare evaluations of the drivers, which sometimes discourages the drivers from improving their driving skills.